In recent years, wearable devices connectable to a network in cooperation with smartphones, etc., have become widely used. Wearable devices currently find application in watches, navigation systems, and sports and health management. In many cases, wearable devices are worn for a long time. Thus, reflective display devices are widely used for wearable devices since such display devices do not use a backlight and consume low energy.
However, as wearable devices are mainly used outdoors, the display devices are exposed to strong external light. Thus, light leakage is easily produced in the semiconductor elements included in a display device. The low-frequency operation of the display device, which reduces energy consumption, is disturbed by such light leakage. The light leakage can be eliminated by providing a metal light-shielding layer facing the semiconductor elements. However, when the metal light-shielding layer is provided, the capacitances formed between a plurality of pixel electrodes having different pixel areas and the metal light-shielding layer differ depending on the pixel electrode. As a result, the drive performance varies among the semiconductor elements. Thus, the display quality is deteriorated.